This invention relates generally to a proximity detection apparatus. In particular, the invention relates to a proximity detection means for a detachable control unit for use with a medical device. Such medical devices include pressure off-loading devices such as inflatable bed mattresses and inflatable cushions, and pressure application devices such as mobile compression devices.
Various compression devices are known for applying compressive pressure to a patient's limb. These types of devices are used to assist in the prevention of deep vein thrombosis (DVT), vascular disorders and the reduction of oedema. The majority of known devices are adapted for use in a hospital setting in which they are used predominantly for the prevention of DVT in patients with a high risk for developing this condition.
Compression therapy may be used in the treatment of patients with venous leg ulcers and compression of the limb achieved by a pneumatic or hydraulic compression device strapped to the patient. Known in the art are mobile compression devices comprising one or more air- or fluid-inflatable cuffs containing one or more cells arranged in an inflatable sleeve for fitting on to a foot, leg or an arm. By means of pressure sensors located in the cells, the device allows for the adjustment of the pressure in the cells of the cuffs dependent on whereabouts on the limb the application of more or less pressure is required during the course of a patient's therapy.
The application of pressure in the cells of the inflatable sleeve can be maintained by an air or fluid pump which is generally located in and operated by an automatic control unit. Accordingly, the pump will typically be associated with an air or fluid conduit system, valves and air or fluid inlet ports. The automatic control unit will typically be a separate component to the sleeve and be electrically powered. Where excessive or deficient pressure is detected by a pressure sensor located in a particular cell, the control unit can activate the pump to restore the intended localized pressure. The control unit will also typically contain the electronic circuitry, air conduits and valves to assist in performing the function of modulating the air or fluid pressure in the cells of the compression device.
In addition to the above-mentioned features, the control unit will generally contain a display (such as a liquid crystal display (LCD)) which provides information to the user or healthcare professional concerning the device.
The control unit may also contain computer hardware containing programmable software for inputting a patient's precise compression therapy requirements. That is, prescribed air or fluid pressure levels throughout the compression device at designated times and for designated periods. Accordingly, a specific therapy for a particular patient can be programmed into the control unit to avoid the need for the patient to manually operate the unit.
The software may also be adapted to keep a record of the pressure in the device over time, thus giving the healthcare professional access to a compliance record of the patient's course of therapy.
A disadvantage of having different modes of use available from a single unit is that it is necessary to switch between the modes in order to obtain the desired function. For instance, for the patient to have a functioning device it is necessary for the control unit to operate the device to provide the selected pressure profile to the limb. For the healthcare professional to obtain compliance data from the device it is necessary for the control unit to display compliance data and not operate the device.
We have now found that it is convenient for the control unit to select between these modes dependent on whether it is present on the device it is operating. In this way, the device can operate in a patient mode to operate the device when present on the device, and in a healthcare professional mode to display compliance data when it is detached from the device.